1. Field of the Invention
The present invention relates to a pedestrian airbag system to be mounted to a hood panel of a vehicle formed of sheet metal at a position near the rear edge thereof. More specifically, the present invention relates to a pedestrian airbag system including an airbag which is inflated so as to cover at least the upper portion of a cowl near the rear edge of the hood panel by being supplied with inflation gas.
2. Description of the Related Art
In the related art, a pedestrian airbag system includes an airbag disposed near the rear end of the hood panel of a vehicle and stored in a case in a folded state. The case is integrally formed with an airbag cover which covers the upper side of the folded airbag, and is formed of synthetic resin (for example, see JP-A-2003-306101).
However, in the pedestrian airbag system in the related art, the case integrated with the airbag cover is firmly secured to a hood panel formed of sheet metal via a bolt or the like.
The synthetic resin case has a larger coefficient of thermal expansion than the hood panel formed of sheet metal approximately by one order of magnitude. Therefore, when the atmospheric temperature is high, the airbag cover portion of the case is significantly deformed with respect to the hood panel by thermal expansion. Consequently, the airbag cover portion of the case causes deterioration of appearance of the airbag system. In particular, a heat source such as an engine is disposed below the hood panel. Therefore, such deformation due to thermal expansion is conspicuously visible.
In the pedestrian airbag system in the related art, there is a type in which an opening allowing the airbag to project is formed on an outer panel of the hood panel, and the opening is covered by a flap portion. The flap portion is formed of sheet metal which is the same as the outer panel (for example, see JP-A-2004-90795).
In such a pedestrian airbag system, the flap portion which opens at the time of deployment and inflation of the airbag is not formed of synthetic resin. Therefore, there is no break due to the difference of material between the flap portion and the outer panel of the hood formed of sheet metal and disposed around the flap portion. Consequently, better design of the portion where the airbag system is mounted is achieved. However, even in the case of the pedestrian airbag system having the flap portion formed of sheet metal, a break showing the contour of the flap portion itself is still visible. Therefore, the pedestrian airbag system described above still needs improvement in design around the mounting position.